1. Field of the Invention
The present invention relates generally to a cap member for covering a plurality of nozzle arrays formed in a nozzle plate of a liquid ejecting head, and also relates generally to a liquid ejecting device comprising such a cap member.
2. Description of Related Art
As an example of liquid ejecting devices, inkjet recording devices capable of color recording using inks of a plurality of colors (such as black, yellow, cyan, and magenta) are known. In such known inkjet recording devices, arrays of nozzles for ejecting respective color inks are provided in a nozzle plate of an inkjet head. A cap member also is provided to enclose and cover the nozzle openings to prevent the ink in the nozzles from drying up or hardening, or both, when the inkjet recording device is kept in the non-recording mode, i.e., in the standby mode.
For example, as shown in FIGS. 11A and 11B, a cap member 90 having two annular lips 91, 92 is used in a 4-color inkjet recording device, as disclosed in U.S. Pat. No. 6,883,896 B2. Lips 91, 92 cover separate four nozzle arrays 10h, 10i, 10j, 10k, which are divided into two segments. Lip 91 covers nozzle array 10h, while lip 92 covers the other three nozzle arrays 10i, 10j, 10k. The four nozzle arrays are divided into two segments, so that ink is withdrawn separately from the two segments, thus, reducing the amount of waste ink. When an ink ejection failure occurs in any nozzle of the inkjet recording device, ink is withdrawn from the nozzles under negative pressure by a maintenance mechanism to restore ejection performance of the nozzles. In this case, if ink is withdrawn by covering all the nozzle arrays with a single lip, ink is withdrawn from all the nozzle arrays regardless of whether or not each nozzle array includes faulty nozzles, resulting in an increase in the amount of waste ink.
As described above, if four nozzle arrays 10h, 10i, 10j, 10k are divided into two segments, and if two lips 91, 92 are provided separately for the respective segments a portion of lip 91 and a portion of lip 92, which are parallel with the nozzle arrays, are disposed at a boundary portion between two adjacent nozzle arrays 10h, 10i, as shown in FIG. 11B. In this case, a distance d between two adjacent nozzle arrays 10h, 10i may resist reduction below a certain limit. Lips 91, 92 experience reduced rigidity and collapse during ink withdrawal if lips 91, 92 are made with a reduced width to decrease distance d. Consequently, a gap is created between lip 91 and the nozzle plate or between lip 92 and the nozzle plate, making ink withdrawal under negative pressure difficult or impossible.
Alternatively, a compact inkjet head, as well as a compact inkjet recording device, in which nozzle arrays are arranged at reduced intervals and at high density is desired. For example, a cap member 100 as shown in FIG. 12A is known. Cap member 100, as described in U.S. Pat. No. 6,471,330 B2, has a lip 101 and a lip 102 that integrally intersect with each other at a portion E and share a partition wall 103 disposed therebetween. Accordingly, a single partition wall 103 is disposed at a boundary portion between two adjacent nozzle arrays.
Nevertheless, in cap member 100, it may be difficult to make lips 101, 102 flush with each other. As shown in FIG. 12B, lips 101, 102 and partition wall 103 are connected at the portion E because potions of lips 101, 102 share partition wall 103. When such a cap member is made by injection molding, grooves for lips are machined into the mold. Because a tool to cut such grooves passes the intersection (i.e., joint) twice, it is difficult to make the depth of the intersecting grooves the same, and a relatively small step may be formed at the bottoms of the intersecting grooves. Consequently, a difference in height h (i.e., a step) is created at the intersection of lips 101, 102 and the flushness between the uppermost surfaces of lips 101, 102 is not ensured.
Even if the cap member having such a step at the intersection of the lips is pressed against the nozzle plate, a clearance may be created between the lip and the nozzle plate, such that the cap member fails to make sealing contact with the nozzle plate. Such a clearance may be eliminated by forcibly contacting the cap member with the nozzle plate. This measure, however, may require use of a greater power source and an increased rigidity of the inkjet recording device, leading to an increase in the production cost.